The Genetic Basis of Adaptation to Climatic Stress in Siberian Indigenous Populations
Our species originated in Africa, and subsequently dispersed to all other continents except Antarctica. During this dispersal, human populations were exposed to a variety of climates that differed substantially from those in their African homeland. Nowhere do these climatic conditions differ more dramatically than in the far northern reaches of Siberia. Indeed, humans represent the only primate species other than the Japanese macaque that has adapted to boreal conditions (where temperatures remain far below freezing for more than half the year) pointing to intense selection pressures that likely drove the enhancement of physiological processes that generate and conserve heat. However, despite the fact that humans have lived in cold climates for millennia, we still know very little about how this process of adaptation occurred at the genetic level. The native populations of Siberia provide the best opportunity to investigate the genetic basis of cold resistance given their long-term residence in some of the coldest climates on earth. While much of northern Europe was under ice throughout the last glacial period, Siberia remained relatively ice free, and archaeological evidence suggests that people inhabited this region for more than 40,000 years. The successful long-term settlement of this area by humans undoubtedly required multiple adaptations to deal with the extended severe cold stress, dramatic variation in photoperiod, and limited and highly variable food resources. This project will gather genome-wide polymorphism data from 15 populations that live across a large area of Siberia, from regions of southern Siberia to the northernmost settlements on the Taymyr peninsula within the Arctic Circle. Patterns of variation in these cold-adapted populations will be compared with those from Central and East Asian populations that live in warmer climates. Particular attention will be paid to genomic regions containing genes that have been previously implicated in cold adaptation, or that function in known pathways connected to energy metabolism or cold-adapted traits. The combination of dense genetic data, wide geographic population coverage, and several powerful methods for detecting the signatures of natural selection will offer the most comprehensive picture of genetic adaptation to cold in humans to date.